Unity Of Object Research Articles

Development of perceptual completion in infancy.

Perceptual completion consists of bridging the gaps imposed by occlusion, such as perceiving the unity of center-occluded objects. It is unknown at present what developmental mechanisms underlie the emergence of functional perceptual completion in infancy. One current debate centers on the role of visible surface motion. According to a core-principles account, perceptual completion emerges simultaneously with the onset of motion discrimination, the sole determinant of unity percepts in infants. According to a contrasting constructivist account, motion discrimination is but one of several independent inputs to perceptual completion. In the present study, 2-month-old infants were tested for both unity perception and motion discrimination in partial-occlusion displays. Motion discrimination obtained under all conditions, even under circumstances in which infants were unable to perceive completion. Four-month-olds showed marked improvements in perceptual completion, most likely because of improvements in information integration. Taken together, these findings support a constructivist view of early perceptual and cognitive development.

Where Infants Look Determines How They See: Eye Movements and Object Perception Performance in 3-Month-Olds.

A fundamental question of perceptual development concerns how infants come to perceive partly hidden objects as unified across a spatial gap imposed by an occluder. Much is known about the time course of development of perceptual completion during the first several months after birth, as well as some of the visual information that supports unity perception in infants. The goal of this investigation was to examine the inputs to this process. We recorded eye movements in 3-month-old infants as they participated in a standard object unity task and found systematic differences in scanning patterns between those infants whose post-habituation preferences were indicative of unity perception versus those infants who did not perceive unity. Perceivers, relative to nonperceivers, scanned more reliably in the vicinity of the visible rod parts and scanned more frequently across the range of rod motion. These results suggest that emerging object concepts are tied closely to available visual information in the environment, and the process of information pickup.

The Influence of Contexton Amodal Completion in 5- and 7-Month-Old Infants

Several investigations have shown that young infants perceive the unity of a center-occluded object when the visible ends of the object undergo common motion but not when the object remains stationary. This study is an extension of earlier investigations on object unity in that it assesses amodal completion of stationary circles in which one half of each is covered by a block. As the experimental stimuli were depicted in the picture plane, only pictorial depth placement cues were available. Furthermore, by employing a stimulus display reported by Palmer (e.g., Palmer, Neff, & Beck, 1996), the role of contextual cues on the perception of the target elements' shape was examined. Results indicated that participants 7 months of age were able to amodally complete the target surfaces if all context elements were full circles. Five-month-old participants, on the other hand, failed to exhibit a comparable visual performance. For them, the most unambiguous situation was one in which the context elements were semicircles. Here, the infants apparently interpreted the target elements to be semicircles as well. The findings suggest that 7-month-olds perceive depth from occlusion cues and are able to use local and global shape completion cues. Younger infants are capable of utilizing contextual shape information, but they apparently fail to conduct amodal completion.

Infants' haptic perception of object unity in rotating displays.

Four-month-old infants were allowed to manipulate, without vision, two rings attached to a bar that permitted each ring to undergo rotary motion against a fixed surface. In different conditions, the relative motions of the rings were rigid, independent, or opposite, and they circled either the same fixed point outside the zone of manipulation or spatially separated points. Infants' perception of the ring assemblies were affected by the nature of the rotary motion in two ways. First, infants perceived a unitary object when the felt ends of the object underwent a common, rigid rotary motion; perception of object unity was stronger in this condition than when the ends underwent either independent or opposite rotary motions. Second, infants perceived two distinct objects when the felt ends of the objects underwent independent rotary motions that centred on distinct fixed points. Perception of the distinctness of the objects was less clear when the ends underwent opposite or independent rotary motions that centred on a common fixed point. These findings provide the first evidence that infants are sensitive to rotary motion patterns and can extrapolate a global pattern of rigid motion from the distinct, local velocities that they produce and experience at their two hands.

Young Infants' Perception of Object Unity in Rotation Displays

Much research has been devoted to questions regarding how infants begin to perceive the unity of partly occluded objects, and it is clear that object motion plays a central role. Little is known, however, about how infants' motion processing skills are used in such tasks. One important kinetic cue for object shape is structure from motion, but its role in unity perception remains unknown. To address this issue, we presented 2‐ and 4‐month‐old infants with displays in which object unity was specified by vertical rotation. After habituation to this display, infants viewed broken and complete versions of the object to test their preference for the broken object, an indication of perception of unity in the occlusion display. Positive evidence for the perception of unity was provided by both age groups. Concomitant edge translation available in 1 condition did not appear to contribute above and beyond simple rotation. These results suggest that structure from motion, and perhaps contour deformation and shading cues, can contribute important information for veridical object percepts in very young infants.

Motion and edge sensitivity in perception of object unity

Although much evidence indicates that young infants perceive unitary objects by analyzing patterns of motion, infants’ abilities to perceive object unity by analyzing Gestalt properties and by integrating distinct views of an object over time are in dispute. To address these controversies, four experiments investigated adults’ and infants’ perception of the unity of a center-occluded, moving rod with misaligned visible edges. Both alignment information and depth information affected adults’ and infants’ perception of object unity in similar ways, and infants perceived object unity by integrating information about object features over time. However, infants perceived a moving, misaligned, three-dimensional object as indeterminate in its connectedness, whereas adults perceived it as connected behind the occluder. These findings indicate that the effectiveness of common motion in specifying unified surfaces across an occluder is reduced by misalignment of edges. Alignment information enhances perception of object unity either by serving directly as information for unity or by optimizing the detectability of motion-carried information for unity. In addition, young infants are able to retain information about edge orientation over short intervals in determining connectedness via a process of spatiotemporal integration.

A constructivist model of infant cognition

We propose six Information-Processing Principles (IPPs) that together describe a constructive, hierarchical system by which infants come to understand objects and events in the world around them. We then demonstrate the applicability of these principles to four specific domains of infant perception and/or cognition, (i.e., form perception, object unity, complex pattern perception, and understanding of causal events). In each case empirical developmental changes appear to be consistent with the IPPs. We then present the Constructivist Learning Architecture, a computational model of infant cognitive development. This model is based on the IPPs, and uses self-organizing, neurally based techniques from Kohonen (1997) and Hebb (1949). We then apply the model to the complex domain of infant understanding of causal events, and replicate many of the developmental changes found empirically. Finally, we discuss the applicability of this constructivist approach to infant cognitive development in general.

Peer Commentaries on Denis Mareschal and Scott P. Johnson’s Learning to perceive object unity: a connectionist account

Developmental ScienceVolume 5, Issue 2 p. 173-175 Connectionist models of infant perceptual and cognitive development Leslie B. Cohen, Corresponding Author Leslie B. Cohen Department of Psychology, University of Texas at Austin, USAAddress for correspondence: Leslie B. Cohen, Department of Psychology, Mezes Hall 330, University of Texas, Austin, TX 78712; e-mail: cohen@psy.utexas.edu or chaput@cs.utexas.eduSearch for more papers by this authorHarold H. Chaput, Corresponding Author Harold H. Chaput Department of Computer Science, University of Texas at Austin, USAAddress for correspondence: Leslie B. Cohen, Department of Psychology, Mezes Hall 330, University of Texas, Austin, TX 78712; e-mail: cohen@psy.utexas.edu or chaput@cs.utexas.eduSearch for more papers by this author Leslie B. Cohen, Corresponding Author Leslie B. Cohen Department of Psychology, University of Texas at Austin, USAAddress for correspondence: Leslie B. Cohen, Department of Psychology, Mezes Hall 330, University of Texas, Austin, TX 78712; e-mail: cohen@psy.utexas.edu or chaput@cs.utexas.eduSearch for more papers by this authorHarold H. Chaput, Corresponding Author Harold H. Chaput Department of Computer Science, University of Texas at Austin, USAAddress for correspondence: Leslie B. Cohen, Department of Psychology, Mezes Hall 330, University of Texas, Austin, TX 78712; e-mail: cohen@psy.utexas.edu or chaput@cs.utexas.eduSearch for more papers by this author First published: 01 May 2002 https://doi.org/10.1111/1467-7687.00218_1Citations: 6Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume5, Issue2May 2002Pages 173-175 RelatedInformation

Modeling infants’ perception of object unity: what have we learned?

Modeling infants’ perception of object unity: what have we learned?

Learning to perceive object unity: a connectionist account

To explore questions of how human infants begin to perceive partly occluded objects, we devised two connectionist models of perceptual development. The models were endowed with an existing ability to detect several kinds of visual information that have been found important in infants’ and adults’ perception of object unity (motion, co‐motion, common motion, relatability, parallelism, texture and T‐junctions). They were then presented with stimuli consisting of either one or two objects and an occluding screen. The models’ task was to determine whether the object or objects were joined when such a percept was ambiguous, after specified amounts of training with events in which a subset of possible visual information was provided. The model that was trained in an enriched environment achieved superior levels of performance and was able to generalize veridical percepts to a wide range of novel stimuli. Implications for perceptual development in humans, current theories of development and origins of knowledge are discussed.

Young Infants' Perception of Unity and Form in Occlusion Displays

Young infants have been reported to perceive the unity of a center-occluded object when the visible ends of the object are aligned and undergo common motion but not when the edges of the object are misaligned (Johnson & Aslin, 1996). Using a recognition-based paradigm, the authors investigated the possibility that past research failed to provide sufficiently sensitive assessments of infants' perception of the unity of misaligned edges in partial occlusion displays. Positive evidence was obtained in 4-month-olds for veridical perception of the motion and location of a hidden region but not its orientation, whereas 7-month-olds, in contrast to the younger infants, appeared to respond to the orientation of the hidden region. Overall, the results suggest that habituation designs tapping recognition processes may be particularly efficacious in revealing infants' perceptual organization. In addition, the findings provide corroborative evidence for the importance of both motion and orientation in young infants' object segregation and for the difficulty in achieving percepts of the global form of a partly occluded object.

The Interpolation of Object and Surface Structure

One of the main theoretical challenges of vision science is to explain how the visual system interpolates missing structure. Two forms of visual completion have been distinguished on the basis of the phenomenological states that they induce. Modal completion refers to the formation of visible surfaces and/or contours in image regions where these properties are not specified locally. Amodal completion refers to the perceived unity of objects that are partially obscured by occluding surfaces. Although these two forms of completion elicit very different phenomenological states, it has been argued that a common mechanism underlies modal and amodal boundary and surface interpolation (the “identity hypothesis”; Kellman & Shipley, 1991; Kellman, 2001). Here, we provide new data, demonstrations, and theoretical principles that challenge this view. We show that modal boundary and surface completion processes exhibit a strong dependence on the prevailing luminance relationships of a scene, whereas amodal completion processes do not. We also demonstrate that the shape of interpolated contours can change when a figure undergoes a transition from a modal to an amodal appearance, in direct contrast to the identity hypothesis. We argue that these and previous results demonstrate that modal and amodal completion do not result from a common interpolation mechanism.

Cases and Biographies: An Essay on Routinization and the Nature of Comparison

▪ Abstract Routines, protocols, and organization charts focus attention, structure cognition, and shape decision making. Participants in organizations, legal systems, and markets compare cases, deciding which protocol governs the treatment of each case in a stream. But situations vary in the extent to which thought and action are effectively governed by routines and standard operating procedures. In less structured or more chaotic situations, biography is an alternative form of analysis that shapes cognition and helps people make sense of otherwise uninterpretable events. Biography and narrative do their work by constructing the causal unity of objects over time rather than by constructing causation from a comparison across similar cases. Using examples such as critically ill infants, animals, heirlooms, the penalty phase of capital trials, juvenile justice, the lower criminal courts, religious relics, and cloth, the paper compares case and biographical analysis in organizations, legal settings, and markets, asking how these different ways of thinking come about and what follows from them.

Do pigeons (Columba livia) perceive object unity?

Human infants perceive two rods moving in concert behind an occluder as one unitary rod. In four experiments we tested whether pigeons also perceive unity of objects. Pigeons were trained on a matching-to-sample task to discriminate between one unitary rod moving at a constant speed and two aligned rods moving together at the same speed. The latter stimulus was identical to the former except for a gap in the center. In experiment1, we tested pigeons in probe trials in which a rectangle occluded the center of the sample rods, to see which comparison stimulus, the unitary rod or the aligned two rods, the subjects would match to the sample. Two of the three subjects pecked at the two rods significantly more often than at the unitary rod. In experiment2, we trained the same pigeons to match the sample rods moving "in front of" the occluder. Pigeons persisted in matching two separate rods to the unitary rod moving in front of the occluder. In experiments3 and 4, we used a parallelogram and an undulating shape as the occluder to alter the shape and the size of the portions above and below the occluder by the motion of the sample rods. Both subjects chose the two rods significantly more often than chance in experiment3 and one of them did so in experiment4. The results suggest that pigeons do not complete occluded portions even though the two elements move in concert. These negative results suggest that some alternative way of identifying objects may have evolved in pigeons.

Visual development in human infants: Binding features, surfaces, and objects

The development of visual binding in humans has been investigated with psychophysical tasks assessing the extent to which young infants achieve perceptual completion of partly occluded objects. These experiments lead to two conclusions. First, neonates are capable of figure-ground segregation, but do not perceive the unity of a centre-occluded object; the ability to perceive object unity emerges over the first several postnatal months. Second, by 4 months, infants rely on a range of Gestalt visual information in perceiving unity, including common motion, alignment, and good form. This developmental pattern is thought to be built on the ability to detect, and then utilize, appropriate visual information in support of the binding of features into surfaces and objects. Evidence from changes in infant attention, computational modelling, and developmental neurophysiology is cited that is consistent with this view.

The Role of Good Form in Young Infants' Perception of Partly Occluded Objects

Young infants have been reported to perceive the unity of a center-occluded object when the visible ends of the object undergo common motion, but not on the basis of stationary information (e.g., P. J. Kellman & E. S. Spelke, 1983). We investigated the possibility that 4-month-old infants will attend to and utilize the global configuration (i.e., the “good form”) of a partly occluded, moving object to perceive its unity and coherence behind the occluder. In the first experiment, infants viewed a partly occluded circle or cross that translated laterally. Infants who habituated in the minimum number of trials (“fast habituators”) showed a reliable posthabituation preference for a broken object over a complete object, indicating perception of unity in the habituation display. Slow habituators exhibited no posthabituation preference. In the second experiment, infants were presented with small ring and cross displays, and the infants looked longer at the broken object. There were no reliable differences in performance between fast and slow habituators. A control group demonstrated no reliable posthabituation preference. In three additional conditions, infants viewed either a partly occluded half ring or a display in which two rod parts were either relatable and nonaligned or nonrelatable. The results indicated that curvature per se provided information in support of completion, in addition to global configuration and motion. Implications for theories of infants' visual development are discussed.

Early perception-action coupling: eye movements and the development of object perception

We investigated the scanning strategies used by 2- to 3.5-month-old infants when viewing partly occluded object displays. Eye movements were recorded with a corneal reflection system as the infants observed stimuli depicting two rod parts above and below an occluding box. Stimulus parameters were chosen on the basis of past research demonstrating the importance of motion, occluder width, and edge alignment to perception of object unity. Results indicated that the infants tailored scanning to display characteristics, engaging in more extensive scanning when unity perception was challenged by a wide occluder or misaligned edges. In addition, older infants tended to scan the lower parts of the displays more frequently than did younger infants. Exploration of individual differences, however, revealed marked contrasts in specific scanning styles across infants. The findings are consistent with views of perceptual development stressing the importance of information processing skills and self-directed action to the acquisition of object knowledge.

Synchronous change and perception of object unity: evidence from adults and infants

Adults and infants display a robust ability to perceive the unity of a center-occluded object when the visible ends of the object undergo common motion (e.g. Kellman, P.J., Spelke, E.S., 1983. Perception of partly occluded objects in infancy. Cognitive Psychology 15, 483–524). Ecologically oriented accounts of this ability focus on the primacy of motion in the perception of segregated objects, but Gestalt theory suggests a broader possibility: observers may perceive object unity by detecting patterns of synchronous change, of which common motion is a special case. We investigated this possibility with observations of adults and 4-month-old infants. Participants viewed a center-occluded object whose visible surfaces were either misaligned or aligned, stationary or moving, and unchanging or synchronously changing in color or brightness in various temporal patterns (e.g. flashing). Both alignment and common motion contributed to adults' perception of object unity, but synchronous color changes did not. For infants, motion was an important determinant of object unity, but other synchronous changes and edge alignment were not. When a stationary object with aligned edges underwent synchronous changes in color or brightness, infants showed high levels of attention to the object, but their perception of its unity appeared to be indeterminate. An inherent preference for fast over slow flash rates, and a novelty preference elicited by a change in rate, both indicated that infants detected the synchronous changes, although they failed to use them as information for object unity. These findings favor ecologically oriented accounts of object perception in which surface motion plays a privileged role.

Unity of objective, diversity of approach: deregulatory telecom developments in Hong Kong and China

Asia-Pacific policy makers in Singapore, Taiwan, Korea, and Malaysia are "benchmarking" their "deregulatory" progress with that of Hong Kong. In contrast to Hong Kong's "fast-track" deregulatory approach, China has been more conservative. This article analyzes the impact of telecommunications (de)regulatory policies on broadband infrastructure investment in Hong Kong and China, respectively.

Mechanisms of development in the perception of object unity

Book synopsis: This book presents the complete collection of peer-reviewed presentations at the 1999 Cognitive Science Society meeting, including papers, poster abstracts, and descriptions of conference symposia. For students and researchers in all areas of cognitive science.